Plane blade grinding jig



y 1960 T. R. CHAMBERS 2,938,311

PLANE BLADE GRINDING JIG Filed March 24, 1958 Fig.1

Thomas R. Chambers 1N VEN TOR.

United States Patent O PLANE BLADE GRINDING J IG Thomas R. Chambers,4616 N. Ozanam Ave., Norridge 31, 111.

This invention relates generally'to a jig and more particularly involvesa novel and improved construction in a jig particularly designed forproperly positioning plane blades adjacent a grinding wheel.

The home hobbyist or busy workman generally sharpens a plane blade orproperly establishes a hollow ground on the blade by simply holding theblade against a moving grinding wheel and feeling his way to a properground. Most often this method is satisfactory for. general purposesbut, however, sometimes an inexperienced person or an inattentive personmay perhaps ruin the blade edge by shotty grinding. The prior art ofcourse shows the development of many blade grinding jig devices but mostof these are not adaptable to home use in that they are somewhat complexand-expensive. Therefore, the development of a simple, inexpensive, andreliable jig would be most welcome by individuals concerned with thisart. It is therefore the principal object of this invention to provide anovel and improved blade grinding jig which is particularlycharacterized by its simplicity, low expense and reliability.

A further object of this invention is to provide a blade grinding jigwhich lends itself to easy and rapid utilization.

It is a still further object of this invention to provide a bladegrinding jig for properly positioning a blade for establishing a goodhollow ground surface.

In accordance with the above stated objects, below are particularlydisclosed the details of construction for a blade grinding jigparticularly designed to properly position a wood plane blade proximatea grinding wheel for establishing a good hollow ground surface on theblade. The jig includes an elongated angle member which is adapted to beheld on a conventional tool rest. A projecting member is transverselyfixed to the elongated member and a pair of threaded aligned aperturespass therethrough. The projecting member is adapted to be slidablyaccommodated in a slot conventionally formed in a plane blade. Theprojecting member guides or aligns the blade properly relative to thegrinding wheel while a winged or locking screw carrying a washer passesthrough the slot, projecting member, and angle member for selectivelylocking the blade relative to the projecting member and angle member.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

Figure 1 is a perspective view of the component jig elements and planeblade;

Figure 2 is a side elevational view illustrating the jig comprising thisinvention in operating position;

Figure 3 is an elevational front view of the jig, blade, and grindingwheel; and

2,938,311 Patented M y 9 ice Figure 4 is a perspective view illustratingthe hollow ground of the blade.

With continuing reference to the drawings and initial reference toFigure 2, the numeral 10 generally represents a conventional grinderhaving a grinding wheel 12 adapted to rotate about an axle 14 driven bythe motor 16 of Figure 3. The motor and grinding wheel are generallysupported on a base as shown at 18 which further carries an arcuate toolrest 20 which is aligned with the driving wheel 12 and has a flat uppersurface 22 which approximates the level of the horizontal diameter ofthe grinding wheel 12.

In order to properly establish a hollow ground as shown at 24 on theblade 26, the 'blade 26 is generally held adjacent the grinding wheel12. "To properly grind the blade 26, however, it is necessarystomaintain the leading edge 28 of the blade 26 horizontal or transverse tothe motion of the grinding wheel 12. .The elements comprising the jigforming this invention aid in maintaining the properrelationship'between the leading edge 28 and the grinding wheel 12. Thejig includes an elongated angle member 30 having a transverse projectingmember 32 fixed thereon as by welding. The elongated member 30 includestwo-leg portions 34 and 36. The projecting member 32 may be fixedto leg34 and project therebe yond. A pair of aligned apertures 38 and 40extend through the, projecting member 32 and the leg 34. alignedapertures38, and'40 are threaded to threadedly receive a'winged lockscrew 42.

The blade 26 has a longitudinal slotted portion 44 adapted to slidablyreceive the projecting member 32 therein. A washer 46, having an outerdiameter greater than the slot width, is accommodated on the wing screw42 over the blade 26. By tightening the winged screw or locking screw 42in the threaded apertures 38 and 40, the washer 46 is brought-to bear onthe blade 26 so as to selectively lock the blade 26 in a desiredposition relative to the projecting member 32 and the angle member 30.The blade 26 and leading edge 28 describe a sliding path prescribed bythe projecting member 32 which is fixed transversely to the leg 34.Therefore, the leading edge 28 will necessarily remain parallel to thevertex line formed by the angle created at the jointure of the legs 34and 36 of the angle member 30. Likewise, the free ends of the legs 34and 36 will also be the vertex line and the leading edge 28.

In the utilization of the jig comprising this invention, the jigelements and the blade are assembled'as indicated in Figure 1. That is,the slot 44 of blade 26 slidably receives and is aligned by projectingmember 32. The winged or locking screw 42 carrying the washer 46 isthreadedly engaged by the apertures 38 and 40. By screwing the screw 42tightly, the washer 46 locks the blade 26 relative to the projectingmember 32 and angle member 30. The legs 36 and 34 are then placed on theflat portion 22 of the tool rest 20 in the manner indicated in Figure 2.The motor 16 is then actuated to turn grinding wheel 12 to establish theproper hollow ground surface 24 on blade 26. The blade 26 and jig areproperly moved reciprocally transverse to the wheel motion forestablishing the proper hollow ground on the entire width of the leadingedge 28. The proper reciprocal motion is indicated by the arrows and at50 and 52 in Figure 3. The operator of course, should be aware that theblade requires frequently cooling to prevent burning of the steel due tothe tremendous friction of the grind ing wheel 12 relative to the blade26. v

After grinding the blade, it is possible that a feathered edge will bedeveloped which can be removed with a few strokes of a fine stone.

parallel to 3 V a The foregoing is considered as illustrative only ofthe principles of the'invention. Further, since numerous modificationsand changes will readily occur to those skilled in the art, it is notdesired to limit the invention to theexact construction and operationshown and described and accordingly, all suitable modifications .and

equivalents may be resorted to, falling within the scope of theinvention as claimed.

What is claimed as new is as follows:

1. A.plane blade grinding jig for properly positioning a plane bladeproximate a grinding wheel for establishing a good hollow groundcomprisingan elongated angle member, said angle member including a pairof identical-rectangular legs, guide means carried by said angle memberfor aligning a plane blade transversely of said angle member exterior tothe angle betweensaid legs, means cooperating with said angle member forretaining said plane blade adjacent said angle member, said guide meansincluding a flat rectangular projecting member fixed to one leg of saidangle member, and aligned apertures in said projecting member and saidangle member.

2. In combination with a plane blade having a longitudinal slot therein,a grinding jig for properly positioning said blade proximate a grindingwheel comprising an elongated angle member, said angle member includinga pair of identical rectangular legs, a flat rectangular projectingmember transversely fi xed to one leg of said .angle member-exterior tothe angle between said legs, said projecting member adapted to slidablyfit within said longitudinal slot whereby said blade is prevented fromrotating relative to said projecting member, and locking means iorselectively locking said plane blade. relative to said angle member andprojecting member.

' 3. In combination with a plane blade having a longitudinal slottherein, a grinding jig for properly positioning said blade proximate agrinding wheel comprising an elongated angle member, said angle memberincluding a pair of identical rectangular legs, a flat rectangularprojecting member transversely fixed to one leg of said angle memberexterior to the angle between said legs, said projecting member adaptedto slidably fit within said longitudinal slot whereby said blade isprevented from rotating relative to said projecting member, and lockingmeans for selectively locking said plane blade relative to said anglemember and projecting member, said locking means including a lock screwand a washer, aligned apertures in said projecting member and said anglemember, said apertures adapted to accommodate said screw to carry saidWasher bearingly against said blade for locking said blade relative tosaid le me ber a d prdesiine m References Cited'in the file of thispatent UNITED STATES PATENTS 147,297 White Feb. 10, 1874 277,958 Stronget'al. May 22, 1883 470,196 Jacobson et al. Mar. 8, 1,892 2,060,927Cristiani Nov. v17', .1936 2,362,711 Mo0re Nov. 14,1944 2,764,187 Zermowski Sept. 25 195.6 FOREIGN PATENTS 21,355 .G eatBrit p on. 11. 1898-695.333

